BACTERIOLOGY. 



Jt> 



Fig. 4. Groupings of bacteria found in the larger zoOglceae. A 

 Single layered tetrads. B, Development of the tetrads, a, b, c 

 into the packets, d, e, the cubical arrangements of cells being 

 shown in d, but not in e. C, Coccus-forms with capsules. D, 

 Development of rods and subsequent breaking up of these into 

 cocci inside of a capsule (Friedlander's Pneumobacillus). E-H, 

 Leuconostoc. E, Arthrospores and F, their germination, and 

 H, their reformation. J and K, Spiral forms in gelatinous en- 

 velopes or capsules, formerly described as the genus My- 

 conostoc. 



sheath and by their true branching, betray an 

 affinity to the fission-algae (Fig.' 5). Both 

 threads and filaments may according to the 

 rigidity of the membrane be motile or non- 

 motile, straight or wavy in outline, or spirally 

 twisted. The spiral threads are closely or 

 loosely wound, stiff or yielding. At times a 

 single filament may be found straight, curved 

 and spirally twisted, at different points. It 

 sometimes happens that motile filaments form 

 loops, or roll up into coils, or wind around one 

 another like whiplashes. Certain kinds show 

 a distinction between base and apex. 



It is often difficult at first sight to determine 



